Question

第一次询问-我在SqlServer 2012中将大小写逻辑和窗口组合在一起时遇到一些问题。我需要展平以下所示的数据结构，因此以后将针对这些结果运行MAX语句。我正在使用case / when逻辑为每个xID指定一个“所有者”。我面临的挑战是，我一直在得到错误的结果，而我无法确定自己在做错什么。

这是大小写/逻辑和表结构。对于“所有者”列，我需要评估三个条件，并试图使用FIRST_VALUE（）选择case语句的输出。 case语句中的逻辑正常工作，但是当我尝试使用窗口函数将值应用于每个xID时，它将返回错误的值。

FIRST_VALUE(case
when [partnerType] = 'Giver' and [partnerAgree] = 'True' then [partnerGroup]
when [partnerType] = 'Impacted' and [partnerAgree] = 'True' then [partnerGroup]
when [Stakeholder No#] = 1 and [partnerAgree] <> 'True' then [partnerGroup]
else Null end) over (partition by [xID] order by [yID])
as 'Owner'

Desired Results --------------------------

|xID|yID| Owner     |partnerType| partnergrp|partnerAgree
|100|  1| grp_Banana|Taker      |grp_Apple  |TRUE
|100|  2| grp_Banana|Giver      |grp_Banana |TRUE
|100|  3| grp_Banana|Taker      |grp_Banana |FALSE
|101|  1| grp_Carrot|Taker      |grp_Carrot |TRUE
|101|  2| grp_Carrot|Giver      |grp_Danish |FALSE
|101|  3| grp_Carrot|Taker      |grp_Banana |TRUE
|101|  4| grp_Carrot|Taker      |grp_Danish |FALSE

Results I'm getting --------------------------

|xID|yID| Owner     |partnerType| partnergrp|partnerAgree
|100|  1| grp_Apple |Taker      |grp_Apple  |TRUE
|100|  2| grp_Apple |Giver      |grp_Banana |TRUE
|100|  3| grp_Apple |Taker      |grp_Banana |FALSE
|101|  1| grp_Carrot|Taker      |grp_Carrot |TRUE
|101|  2| grp_Carrot|Giver      |grp_Danish |FALSE
|101|  3| grp_Carrot|Taker      |grp_Banana |TRUE
|101|  4| grp_Carrot|Taker      |grp_Danish |FALSE

第一个表显示了我期望的结果，但是代码在第二个表中产生了值。示例：对于xID = 100，我希望所有者为grp_Banana，但是我的代码返回grp_Apple。对于xID = 101，我得到了正确的答案，但是原因有误。窗口函数似乎对任何结果集都采用第一个yID。

感谢您的帮助。另外，我愿意不使用开窗功能，这似乎是正确的方向。

Answer 1

除非您的数据库支持ignore null s参数，否则这很棘手。您可以使用两个窗口功能来做到这一点：

max(case when yid = yid_special then partnerGroup end) over (partition by xid) as Owner
from (select . . . ,
             min(case when partnerType = 'Giver' and [partnerAgree] = 'True' then yid
                      when partnerType = 'Impacted' and [partnerAgree] = 'True' then yid
                      when [Stakeholder No#] = 1 and [partnerAgree] <> 'True' then yid
                 end) over (partition by xid) as yid_special

您也许还可以使用first_value()来编写此代码：

first_value(partnerGroup) over
    (partition by xid
     order by (case when partnerType = 'Giver' and [partnerAgree] = 'True' then yid
                    when partnerType = 'Impacted' and [partnerAgree] = 'True' then yid
                    when [Stakeholder No#] = 1 and [partnerAgree] <> 'True' then yid
                    else 999999
                end) 
    ) as owner

Answer 2

使用@ Gordon-Linoff的建议，我能够解决我的问题。这是修改后的代码。在Order By中看到Gordon对case语句的使用使我意识到为什么我的代码有时选择错误的值。因为我只是基于他的方法，所以我相信他的答案。非常感谢。

, FIRST_VALUE(
case
when [partnerType] = 'Remediator' and [partnerAgree] = 'True' then [partnerGroup]
when [partnerType] = 'Impacted' and [partnerAgree] = 'True' then [partnerGroup]
when [yID] = 1 and [partnerAgree] <> 'True' then [partnerGroup]
else [partnerGroup] end) 
over 
(partition by [Incident ID] order by
case 
when [partnerType] = 'Remediator' and [partnerAgree] = 'True' then 1
when [partnerType] = 'Impacted' and [partnerAgree] = 'True' then 2
when [yID] = 1 and [partnerAgree] <> 'True' then 3   
else 100
end
)
as 'Owner'

SQL-使用开窗和case语句展平表格

2 个答案: